Traditionally, extruders are used to melt, homogenize, and pump polymers through various dies. In the past couple of decades, extruders have found use in various polymer modification applications. See Costas Tzonganakis, “Reactive Extrusion of Polymers: A Review,” Adv. in Polymer Tech. 9(4): 321-330 (1989).
For example, U.S. Pat. No. 6,228,213 to Hanna et al. proposes acid hydrolysis of cellulose in an extruder to form microcrystalline cellulose.
U.S. Pat. No. 6,117,947 to Wang et al. propose modifying poly(ethylene oxide) by grafting polar vinyl monomers, such as poly(ethylene glycol)methacrylates and 2-hydroxyethyl methacrylate, onto the poly(ethylene oxide) utilizing a reactive extrusion process.
U.S. Pat. No. 6,087,468 to Hoeks et al. proposes reactive extrusion of an organic salt branching agent with linear polycarbonate resin.
U.S. Pat. No. 6,022,941 to Mestanza et al. proposes the branching of polycarbonate by reactive extrusion using free radical chemistry.
U.S. Pat. No. 5,952,433 to Wang et al. proposes a method of grafting polar groups onto polyactides by reactive extrusion.
U.S. Pat. No. 4,501,859 to Newman et al. proposes continuous halogenation of polymers in an extruder-reactor. The polymer passes through three extruder-reactor zones under controlled conditions to achieve halogenation: feed, reaction, neutralization, and optionally a wash and exit zone.
There is a need in the art for improved reactive extrusion methods.